Stuck in reverse:: loss of LC1 in Trypanosoma brucei disrupts outer dynein arms and leads to reverse flagellar beat and backward movement
Stuck in reverse:: loss of LC1 in Trypanosoma brucei disrupts outer dynein arms and leads to reverse flagellar beat and backward movement
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DOI：
10.1242/jcs.004846
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发表时间：
2007-05-01
影响因子：
4
通讯作者：
Hill, Kent L.
中科院分区：
文献类型：
--
作者：
Baron, Desiree M.;Kabututu, Zakayi P.;Hill, Kent L.
轴丝动力蛋白是鞭毛运动的多亚基分子马达。动力蛋白轻链1（LC 1）已在莱茵衣藻中得到充分研究，并且在所有动力蛋白组分中是唯一已知直接结合动力蛋白重链催化马达结构域的蛋白质。然而，LC 1在动力蛋白组装和/或功能中的作用是未知的，因为以前没有突变体。我们确定了LC 1同源物（TbLC 1）在布氏锥虫，并研究了其在锥虫鞭毛运动表位标签和RNAi研究的作用。TbLC 1定位沿着鞭毛的长度和分区之间的轴丝和可溶性组分洗涤剂和盐提取。TbLC 1基因表达的RNAi沉默导致锥虫鞭毛运动的标志性优势尖端到基部搏动的完全丧失，以及伴随出现的持续反向搏动，其从基部到尖端传播并驱动细胞反向运动。超微结构分析表明，外臂动力蛋白被破坏的TbLC 1突变体。因此，LC 1是T细胞动力蛋白稳定组装和前向运动所必需的。布鲁塞。我们的工作提供了LC 1在任何生物体中的第一个功能分析。结合T.布氏杆菌DNAI 1突变体[Branche等人（2006）.轴丝成分在锥虫运动中的保守性和特异性功能。《细胞科学杂志》119，3443- 3455]，我们的数据表明外臂动力蛋白在T. brucei和C.莱因哈德氏菌了解这些差异将提供一个更强大的描述鞭毛运动的基本机制，并将有助于努力利用锥虫鞭毛作为药物靶点。
Axonemal dyneins are multisubunit molecular motors that provide the driving force for flagellar motility. Dynein light chain 1 (LC1) has been well studied in Chlamydomonas reinhardtii and is unique among all dynein components as the only protein known to bind directly to the catalytic motor domain of the dynein heavy chain. However, the role of LC1 in dynein assembly and/or function is unknown because no mutants have previously been available. We identified an LC1 homologue (TbLC1) in Trypanosoma brucei and have investigated its role in trypanosome flagellar motility using epitope tagging and RNAi studies. TbLC1 is localized along the length of the flagellum and partitions between the axoneme and soluble fractions following detergent and salt extraction. RNAi silencing of TbLC1 gene expression results in the complete loss of the dominant tip-to-base beat that is a hallmark of trypanosome flagellar motility and the concomitant emergence of a sustained reverse beat that propagates base-to-tip and drives cell movement in reverse. Ultrastructure analysis revealed that outer arm dyneins are disrupted in TbLC1 mutants. Therefore LC1 is required for stable dynein assembly and forward motility in T. brucei. Our work provides the first functional analysis of LC1 in any organism. Together with the recent findings in T. brucei DNAI1 mutants [Branche et al. ( 2006). Conserved and specific functions of axoneme components in trypanosome motility. J. Cell Sci. 119, 3443- 3455], our data indicate functionally specialized roles for outer arm dyneins in T. brucei and C. reinhardtii. Understanding these differences will provide a more robust description of the fundamental mechanisms underlying flagellar motility and will aid efforts to exploit the trypanosome flagellum as a drug target.